A semiconductor apparatus that employs a power semiconductors device includes that having a semiconductor device sealed with epoxy resin or a similar thermosetting resin, i.e., a mold sealed type, and that having a semiconductor device sealed with gelated resin, i.e., a gel sealed type. In particular, the mold sealed semiconductor apparatus is small in size and excellent in reliability, and handleable, and it is thus used widely for controlling air conditioners and the like. Furthermore, in recent years, it is also used to control an automobile's motive power to drive a motor.
Normally, a semiconductor device is produced as follows: a large number of semiconductor devices provided on a semiconducting crystal substrate (hereinafter referred to as a semiconductor substrate) are diced into individual pieces (or chips). A semiconductor device receiving high voltage exceeding several hundreds volts for operation, seeks insulation between an upper electrode pad serving as a major electrode and a metal frame's side, and accordingly, the upper electrode pad is surrounded by an insulating film formed of a resin material. Note, however, that the semiconductor devices are diced with a dicing blade, and to avoid clogging the dicing blade, the insulating layer is not provided in the dicing region. The semiconductor device is bonded to the metal frame, and thereafter wired and sealed with thermosetting resin, and a semiconductor apparatus is thus completed.
When the above semiconductor apparatus is in operation, the semiconductor device generates heat, which causes thermal stress between the semiconductor device and the sealant resin. This thermal stress is caused as the semiconductor chip and the sealant resin have their respective coefficients of thermal expansion with a difference therebetween, and the thermal stress is also caused as the sealant resin sets and thus shrinks. Normally, the semiconductor device is a square semiconductor chip and has four corners with their ends experiencing maximum stress, and accordingly, may have the four corners defectively peeled off at an adhesive interface.
A conventional semiconductor apparatus has a semiconductor chip exposed in a dicing region covered with a silane based resin film to allow the chip to adhere to a sealant resin via enhanced adhesive strength.